It all started yesterday when I reset the soft close pump by pulling the fuse. Soft close has not been working and I have been limping by without it. So I found out yesterday when the soft close pump was operating that it somehow was draining the battery. I figure it is leaking and continuing to run the pump. So I connected my Sears Brand 10 amp charger to the battery while still connected to the w140 and later on, to make matters worse, I inserted the key and turned on the accessorys while the charger was still charging the battery. When I turned on the key to accessory I heard a somewhat screeching fan noise coming from somewhere behind the passenger side dash and I turned the key off and removed it. (But not before I tried to start the car but nothing, no cranking and no clicking.) Thoroughly shaken by my ability to make big mistakes I left the car alone, disconnected the charger and tried to sleep.
The battery was completely dead this morning so I removed the battery and connected the battery to the charger and it should take between 12 to 24 hours to fully charge. I will check at 12 hours.
I am worried that I did serious damage to the electrical system of the w140.
If I were able to get back to where I was before charging, I would pull the fuse for the soft close pump and move forward with a repair this week (go in and at lease look and listen to the pump operate). But now I have a bigger potential problem.
Tomorrow I install a fully charged battery and pray.
What else should I do?

Background on car. 1995 s500 w140 one owner car with 102k mi. I have had if for one year. It is reliable and mostly working well (until I zapped it.)

 

So, it looks like there was no serious damage by my charging the w140 battery with a sears 10 amp charger while the battery was still connected to the car (exposed to the cars open circuit).Great news. I discovered this when I charged the battery unattached to the car to what I believe to be fully charged. I tested it and the multi meter and it read 15 so I think that was a correct 15 amp output. The car started fine with no god awful screaking fan noises from the dashboard. So I am happy that all I have to deal with now is my non latching trunk and soft close (non) function and maybe if I need a new battery because these cars seem to need a very high functioning battery and I may have damaged it because of the complete draining and fast recharge. The following morning the battery had run down again. So i am working through it. Sorry for the false alarm after my low voltage scare. I love my car and I was sure that I blew it up.

New question: I tried to lock the truck manually by using the proceedure in owners manual where I use the button inside the trunk lid and by pushing the lock device in. this did not work. no clicking no movement at all. I may be doing something wrong but it does not seem so. can anyone help. these truck mechanism seem to be ground zero on these cars. Thanks.